Fiber optic sensing systems have been used in a number of applications including perimeter security, acoustic sensing, and leak detection. Examples of conventional fiber optic sensing systems include (1) modal interference-based systems; (2) time-correlated Mach-Zehnder interferometer-based systems; and (3) coherent Rayleigh backscattering-based systems. Each of these conventional systems suffers from certain deficiencies.
For example, modal interference-based systems provide very limited information about an event such as the location and/or time of an event. Further, such systems have difficulty distinguishing between multiple simultaneous events. Time-correlated Mach-Zehnder-based systems have difficulty discerning continuous events (e.g., a pipe leak). Coherent Rayleigh backscattering-based systems suffer from high interrogator costs and limited sensitivity. Further, certain of these conventional systems utilize photonics boxes located throughout an array that require electrical power to be provided locally, rendering such systems impractical for long distance applications such as border security.
Thus, a need exists for, and it would be desirable to provide, improved optical detection systems.